Usage of asynchronous response data in asynchronous components

Question

Below is the parent component and child component:

export default {
    name : 'parentNode',
    mounted: function () {
        var that = this;

        if (that.$store.state.auth.isAuthenticated) {
        
            that.$store.dispatch(ActionsType.GET_ALLCOINLIST).then(function (data) {
            // I want to use this store data in child components.
                that.$store.state.main.data = data;
            });
        }
    },
};

export default {
    name : 'childNode',
    data : function(){
        return {
            childData : {}
        }
    },
    mounted : function(){
        //How should I check if the data is loaded or not?
    },
    computed : {
        childData : function(){
            return this.$store.state.main.data;
        }
    },
    watch : {
        childData : function(){
            this.makeChart();
        }
    },
    methods : {
        makeChart : function(){
            console.log('this function make a chart.');
        }
    }
}

I want to draw a new chart whenever the $store(vuex) data changes. However, since the response of this data is asynchronous, when the child component is loaded, it may or may not have received the data (in the parent component).

I always want to draw a chart with the data I received when the child component was initially loaded. The components of Vue are also asynchronously loaded, so in this case, how can I control it? As of now, if the child component is initially loaded, the chart may or may not be drawn.

Answer 1

You can use mapState() and watch():

import Vue from "https://cdn.skypack.dev/vue@2.6.14";
import * as vuex from "https://cdn.skypack.dev/vuex@3.6.2";

Vue.use(vuex)

var store = new vuex.Store({
  state: {
    count: 1,
    isLoaded: false, // mutate that when async call is finished
  },
  mutations: {
    increment (state) {
      state.count++
    }
  },
  actions: {
    init() {
      setInterval(() => this.commit('increment'), 1000) // replace this with async call and mutate isLoaded in then()
    }
  }
});

var app = new Vue({
  el: '#app',
  store,
  data() {
    return {
    }
  }, computed: {
    ...vuex.mapState([
      'count'
    ]),
  },
    watch: {
      count() {
        console.log('watch count', this.count)
      }
    },
  mounted() {
    this.$store.dispatch('init')
  }
})